java - ArrayList，双包含

Question

private static boolean moreThanOnce(ArrayList<Integer> list, int number) {
    if (list.contains(number)) {
        return true;
    }
    return false;
}

我如何使用 list.contains检查是否在列表中多次找到该号码？我可以用 for 做一个方法循环，但我想知道是否可以使用 .contains .感谢帮助!

Answer 1

您可以使用 Stream s:

private static boolean moreThanOnce(ArrayList<Integer> list, int number) {
    return list.stream()
               .filter(i -> i.equals (number))
               .limit(2) // this guarantees that you would stop iterating over the
                         // elements of the Stream once you find more than one element
                         // equal to number
               .count() > 1;
}